Vegetation survey and soil property measurement
Within each sampling quadrat, we measured plant height, percentage coverage, aboveground biomass (AGB), and belowground biomass (BGB) of herbaceous species at August 2020 according to the standard filed vegetation survey method (Zhao et al., 2023). Following the vegetation sampling, soil samples (0–10 cm in depths) were collected from each quadrat for measuring soil property. soil organic carbon (SOC), soil total nitrogen (STN), soil inorganic nitrogen (NH4+−N and NO3−N), soil microbial biomass carbon (MBC) and nitrogen (MBN). Soil organic carbon (SOC) and soil total nitrogen (STN) contents were measured determined by an elementary analyzer (Vario EL III, Elementar, Germany). Soil inorganic nitrogen (NO3N and NH4+−N) contents were measured using auto-analyzer (Auto Analyzer 3, Bran Luebbe, Germany). The soil microbial biomass carbon (MBC) and nitrogen (MBN) contents were measured by the chloroform fumigation-extraction method.